PHOTOSHOP: My image turned magenta

I already typed this all out but this site didn't indicate it was posted.

I am working on an ad that is due Monday. Because it will be printed I was working in cmyk. However, I pressed 'command' plus some unknown key on the left side of the keyboard, not the one I meant to hit, and my image turned magenta. I am freaking out because I can't find a way to get full color back. The action is not in the 'history' and command z didn't change anything either.

I am desperate. Starting over is not an option... can anyone help me? Please USING CS4 ON A MAC 10.4.9